What Makes Things Smell?

Posted on 14th December 2017

Through our extensive work in providing odour abatement solutions, the team here at Parsons have helped to combat and dispel many kinds of odours over the years. Dealing with things that smell (including some of the worst smells in the world) is just part of another day for the team here, and we’re proud to deliver systems that provide complete odour abatement across a number of sectors and industries.

The science of odour, including exactly what causes something to smell and how our noses interpret it, is an interesting study in both biology and chemistry. Odours themselves are chemical reactions, but through the nose, we access and understand the information via our olfactory system, the part of our bodies that processes and interprets smells.

What exactly is a smell?

Smells are caused by one or more volatilized chemical compounds. The compounds tend to be light and therefore they can travel in the air as molecules. When these travel in the air, they are detected by the epithelium, a patch of mucus-covered tissue in the nose, and are also trapped by cilia, tiny hairs inside the nose. The epithelium is filled with olfactory receptors (also known as neurons) and these are what process the smell to the brain and central nervous system for more information.

We’ve broken the key stages that go into the process of detecting an odour by the human nose:

Volatilized chemical compounds are present in the air.

These compounds enter the olfactory system via the nose.

Compounds enter the epithelium and cilia also come into contact with the compounds.

Neurons in the olfactory system fire as the cilia detect the compounds. Signals are sent through the olfactory nerve to the olfactory bulb in the brain, a part of the limbic systems.

The brain begins to interpret the detected smell based on memory and relation to the substances present. This information is also relayed through the central nervous system to generate an appropriate response (i.e. moving away from a roadkill carcass, picking out the right bunch of flowers).

The sense of smell is very closely linked to the sense of taste – everyone tends to notice that their food tastes different when they have a cold, and that’s because when you chew food it releases compounds which are processed and contribute to the taste of the food you are eating. If your nose is blocked, these compounds can’t reach the necessary neurons and so many foods taste much blander than they would normally.

Toby is our olfactory resident here at Parsons.

Animal facts: sniffing champions

The sense of smell is highly important in the animal kingdom. Many animals rely on their acute sense of smell to help them find food, water, and mates. Of all mammals, bears have the best sense of smell, with polar bears able to smell a seal through a metre of snow and from over half a mile away!

Black bears and grizzly bears are similarly impressive, being able to track food sources underwater and almost twenty miles away from them. In the insect world, male luna moths have the best noses, with males able to detect the pheromones of a female from over six miles away. Many animals have special adaptations to help them smell specific scents – for example, elephants can smell water, particularly underground water, from over 12 miles away.

Our own ‘olfactory resident’ is Toby, the border collie. A dog’s sense of smell is up to 50 times greater than a human’s, and dogs have been trained to sniff out drugs, explosives, blood, people (such as search and rescue), money, electronics, wildlife, plants, and even cancer.

If you need a solution to your odour issues, contact Parsons today and see how we can help. Our rental solutions are an excellent way of solving odour issues without the need for a huge capital expenditure – and you’ll get to the see results of our plant without committing to an expensive purchase.

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